Temperatures at streams in the Seoul region have risen by as much as three-point-one degrees Celsius this year compared to the average between 1994 and 2020. 

The Seoul Research Institute of Public Health and Environment disclosed the results on Thursday after conducting temperature checks at the Han River's two main streams and three tributaries. 

The institute found that the average high temperature at Anyang Stream was 31-point-two degrees last month, up three-point-one degrees from previous years. 

This is the highest figure in 27 years and one degree higher than the average high temperature in July 2018, when the nation had its worst heat wave season. 

The high temperature at the Noryangjin main stream was 26-point-seven degrees on average this year, up two-point-six degrees from previous years. 

The institute said tributaries are shallower and have less water flow than main streams, which make them more sensitive to temperature changes. It voiced concern that temperature increases in small rivers could lead to fish deaths.